This invention relates to the art of slaughtering and in particular to a device for stunning birds before they are killed.
In modern day poultry processing, live birds are suspended from a foot shackle type overhead conveyor and then are advanced to a station where they are automatically killed. En route to this station it is desirable to stun the birds so that they are relatively immobile, brain activity is decreased, and in proper position for the killing device. Various stunning devices are disclosed in the prior art and these typically involve passing an electrical current through each bird. One example is found in U.S. Pat. No. 3,564,645 wherein an alternating current is impressed across two electrodes one of which communicates with the feet of the suspended bird and the other of which is in the form of an electrolyte bath which the heads of the birds contact. Other pertinent devices are shown in U.S. Pat. Nos. 3,702,017; 3,828,397; 3,918,123; and 4,092,761.
A stunner should uniformly stun the birds passing through it despite the birds' various behavior on approach to the stunner. The degree of stunning is important; that is, the bird should be rendered immobile yet not be over-stunned since the latter can cause physiological damage and thus decrease yields. Furthermore, a stunner should be inexpensive to produce and economical of electricity and electrolyte in use.
Commonly used prior art stunners are notoriously wasteful of electrolyte, in particular, because not only is a certain amount of electrolyte carried off by the birds as they are passed through the stunner, but also the heads of the birds tend to plow or push water out of the stunner basin. And, despite the numerous stunner designs available, none provides what we consider acceptable uniformity in its effect from bird to bird.
In view of the foregoing, one object to the invention is to produce a device for stunning poultry that minimizes the consumption of electrolyte per bird.
Another object to the invention is to control the concentration of an electrolyte solution inasmuch as the stunning effect is highly dependent upon the concentration.
Another object is to minimize the unit electrical consumption in such a stunner.
A further object is to maximize the certainty that a given bird will be adequately stunned while preventing over-stunning and consequent tissue and joint damage.
Yet another object is to achieve the foregoing with a simple and inexpensive apparatus not dependent upon complex controllers and the like and not requiring frequent adjustment.
These and other objects are met by a stunner comprising a conveyor for carrying suspended birds along a predetermined path, an electrolyte bath extending below the conveyor for a portion for the path, means for impressing an electrical potential between the conveyor and the bath, means for aerating the electrolyte, and means for recovering electrolyte from the birds downstream from said basin.